Chapter 10

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School

University of Toronto Scarborough

Department

Psychology

Course

PSYB51H3

Professor

Matthias Niemeier

Semester

Winter

Description

Chapter 10: Hearing in the Environment Sound Localization Having 2 ears crucial for determining auditory locations 2 potential types of information for determining source of sound: o Even though sound travels very fast, pressure wave will not arrive at both ears at same time Sounds arrive sooner, albeit very slightly, at ear closer to source o Intensity of sound greater at ear closer to source Interaural Time Difference (ITD) If source to the left, sound will reach left ear first, if source to right, sound reach right ear first o Can tell whether sound coming from right or left by determining which ear receives sound first Azimuth: describe locations on imaginary circle that extends around us- front, back, left, right in horizontal plane Medial superior olives (MSOs): first places in auditory system where inputs from both ears converge Interaural Level Difference (ILD) Sounds more intense at ear closer to sound source because head partially blocks sound pressure wave from reaching opposite ear Properties of ILD relevant for auditory localization similar to ITD: o Sounds more intense at ear closer to sound source, less intense at ear further away from source o ILD largest at 90 and -90 degrees, nonexistent at 0 degrees (directly in front) and 180 degrees (directly behind) o Between these 2 extremes, ILD generally correlates with angle of sound source, but because of irregular shape of head, correlation not quite as great as it is with ITDs Neurons sensitive to intensity difference between 2 ears found in lateral superior olives (LSOs): receives both excitatory and inhibitory inpu